Layer-by-layer (LbL) assembly, a directed assembly technique based on complementary chemical interactions, can create nanoscale, conformal films with a broad range of therapeutics. LBL adsorption of oppositely charged polyelectrolytes on substrates can be used to fabricate thin multi-layer films for controlled release of bioactive agents such as drugs. Nevertheless, LbL-based methods of delivering drugs have been traditionally based on the formation of uniform films from which drugs escape via diffusion. Such diffusion-based release can limit or eliminate the opportunity for controlled sequential delivery of drugs released from the surface to the surrounding medium. With such films, a typical diffusive, nonlinear drug release pattern is typically observed, and rarely is diffusion-controlled release from LbL films sustained for more than a few hours. Also, processing methods for such films may involve harsh solvents, in addition to acidic byproducts of degradation, which may destroy the agent intended to be delivered.
Controlled release may be achieved using decomposable thin films comprising multilayer units comprised of polymer layers of alternating charge. Bioactive agents are released in a controlled fashion from the films as layers of polymers degrade.